H5N1 is a strain of -

Avian influenza In 1997, human cases of influenza caused by avian influenza viruses 64/1/5N) were detected in Hongkong during an extensive outbreak of influenza in poultry. All these cases were associated with contact with infected poultry. Efficient person to person transmission has not been observed to date. Mortality rates have been high (60%) and clinical manifestations have differed somewhat from those associated with typical outbreaks of influenza. Transmission of avian influenza A/H7N7 viruses from infected poultry to humans has been observed in the Netherlands, resulting predominantly in cases of conjunctivitis and some respiratory illness. Infection with A/H9N2 viruses along with mild respiratory illness has been reported in children in Hongkong. Because of the absence of widespread immunity to H5, H7 and H9 viruses, concern has been raised that avian-to-human transmission may be the basic for the emergence of pandemic strains.